With the development of science and technology, 3D display, particularly glasses-free 3D display, has become an inevitable trend in the display field. The principle of the currently common glasses-free 3D display technology is as follows: dividing an image into two images adapted to be viewed by a left eye and a right eye from different angles, and present a plurality of mutually spaced left visual fields and right visual fields in front of a display panel with the help of a grating. When a left eye of a viewer is disposed in the left visual field and a right eye is disposed in the right visual field corresponding to the left visual field, the left eye of the viewer can view the corresponding left-eye image and the right eye can view the corresponding right-eye image. The left-eye image and the right-eye image are a pair of stereo images. Thus, the brain can integrate the images into a 3D image, and hence the viewer can enjoy the 3D stereo image.